Field of the Invention
The invention relates to a power supply control method and, more particularly, to a power supply control method and a portable electronic device using the same.
Description of the Related Art
As the development of science technology, various portable electronic devices, such as a tablet computer, a personal digital assistant (PDA), a laptop computer and a smart phone, become necessary in daily life.
Conventionally, the portable electronic device is charged or discharged via power adaptor which conforms to a universal serial bus (USB) power delivery (PD) standard. The power adaptor is connected to a USB interface of the portable electronic device via power lines to charge the portable electronic device.
Conventionally, different power adaptors have different rated output power or maximum output power, and different portable electronic devices have different load settings. In an embodiment, the rated output power of the power adaptor is 5V/1 A. When the load of the portable electronic device is set to extract the current of 1 A, the power adaptor generates the output current of 1 A when the portable electronic device is connected to the power adaptor. When the load of the portable electronic device is set to extract the current of 0.5 A, the power adaptor generates the output current of 0.5 A when the portable electronic device is connected to the power adaptor.
As stated above, a portable electronic device extracts the current from the power adaptor according to a constant load setting, therefore, when the specification of the portable electronic device is matched with the rated output power of the power adaptor, the power adaptor achieves its highest power supply efficiency.
However, when the rated output power of the power adaptor is not matched with the load specification of the portable electronic device, the power adaptor supplies power inefficiently. Moreover, when the load of the portable electronic device is too heavy, the power adaptor overloads, which brings risks in usage.